Micro-Electro-Mechanical-System Device with Particles Blocking Function and Method for Making Same

ABSTRACT

The present invention discloses a MEMS device with particles blocking function, and a method for making the MEMS device. The MEMS device comprises: a substrate on which is formed a MEMS device region; and a particles blocking layer deposited on the substrate.

BACKGROUND

1. Field of Invention

The present invention relates to a micro-electro-mechanical system(MEMS) device and a method for making the MEMS device, in particular toa MEMS device with particles blocking function and a method for makingit.

2. Description of Related Art

MEMS devices are used in a wide variety of products such asmicro-acoustical sensor, gyro-sensor, accelerometer, etc. A MEMS deviceusually has a mechanical structure part located on top of the overalldevice, and therefore if particles fall into the device, the operationof the mechanical structure may be adversely affected. Thus, it isdesired to provide a MEMS device with particles blocking function.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a MEMS devicewith particles blocking function.

It is another objective of the present invention to provide a method formaking a MEMS device with particles blocking function, which is fullycompatible with a standard CMOS manufacturing process.

In accordance with the foregoing and other objectives of the presentinvention, from one aspect, the present invention discloses a MEMSdevice with particles blocking function, comprising: a substrate onwhich is formed a MEMS device region; and a particles blocking layerdeposited on the substrate.

In another aspect, the present invention discloses a method for making aMEMS device with particles blocking function, comprising: providing asubstrate; forming a MEMS device region on the substrate; and depositinga particles blocking layer for blocking particles.

The particles blocking layer in the above-mentioned MEMS device andmethod is preferably made of a porous material.

A preferred material for the particles blocking layer is a materialreferred to as Black Diamond in the semiconductor industry.

It is to be understood that both the foregoing general description andthe following detailed description are provided as examples, forillustration and not for limiting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings.

FIGS. 1A-1D show an embodiment according to the present invention.

FIGS. 2A-2D show another embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings as referred to throughout the description of the presentinvention are for illustration only, but not drawn according to actualscale.

Referring to FIG. 1A for the first embodiment of the present invention,a zero-layer wafer substrate 11 is provided, which for example can be asilicon wafer so that the process is compatible with a standard CMOSprocess. Next, transistor devices can be formed by standard CMOS processsteps as required (not shown), followed by deposition, lithography andetch steps to form interconnection including a contact layer 12 a, metallayers 13, and via layers 12 b. In one embodiment, the contact layer andthe via layers can be made of tungsten; the metal layers can be made ofaluminum; and the dielectric layer can be made of oxides such as silicondioxide. Other conductive or dielectric materials can be used to replacewhat are suggested above, and the structure can include more or lessnumber of metal layers. The pattern of each of the layers 12 a, 12 b and13 is thus that a sacrificial region 14 a and an isolation region 14 bare formed therein. The detailed pattern of each layer is not shown forsimplicity of the drawings. The regions 14 a and 14 b may be made of thesame or different materials; in this embodiment they are both made of anoxide, such as silicon dioxide. The sacrificial region 14 a is providedso that the suspension structure of the MEMS device to be manufacturedis separated from the silicon substrate (also referring to FIG. 1D). Theisolation region 14 b is provided to isolate the MEMS device region 100from the other circuit region 200; its cross sectional pattern need notbe exactly as shown but can be of any other shape.

Referring to FIG. 1B, a passivation layer 15 is formed on the substrate.The passivation layer may be a single or composite layer, such as anoxide layer, a nitride layer or a bi-layer structure including an oxidelayer and a nitride layer. Next, a mask layer 16 is deposited on thesubstrate and patterned to open an area 20 so that an etch step can takeplace later through the opened area 20. The mask layer 16 may be made ofa material such as poly-silicon, amorphous-silicon, or metal.

Referring to FIG. 1C, a particles blocking layer 17 is deposited on thesubstrate. The particles blocking layer 17 prevents particles fromfalling into the MEMS device after the MEMS device is finished.Preferably, the particles blocking layer 17 is made of a porous materialso that the oxide in the sacrificial region 14 a can be better removedin a later etch step. According to the present invention, a preferredmaterial for the particles blocking layer 17 is a material referred toas Black Diamond in the semiconductor industry.

Referring to FIG. 1D, an etch step is performed to remove the oxide inthe sacrificial region 14 a. The etch for example can be HF (hydrogenfluoride) vapor etch. Thus, a desired MEMS device is formed; the MEMSdevice has a particles blocking function, preventing particles fromfalling into the mechanical structure of the MEMS device.

In the method described above, the mask layer 16 and the particlesblocking layer 17 can be formed in a reversed order. FIGS. 2A-2D show asecond embodiment of the present invention to explain this. Thedescription for FIG. 2A is omitted because it is the same as FIG. 1A.

Referring to FIG. 2B, after FIG. 2A, a passivation layer 15 is formed onthe substrate. As stated above, the passivation layer 15 may be a singleor composite layer, such as an oxide layer, a nitride layer or abi-layer structure including an oxide layer and a nitride layer. Next, aparticles blocking layer 17 (not the mask layer 16 in the previousembodiment) is deposited on the substrate. The particles blocking layer17 is preferably made of a porous material, such as Black Diamond.

Referring to FIG. 2C, next a mask layer 16 is deposited on the substrateand patterned. The mask layer 16 may be made of a material such aspoly-silicon, amorphous-silicon, or metal.

Referring to FIG. 2D, an etch step is performed to remove the oxide inthe sacrificial region 14 a. The etch for example can be HF (hydrogenfluoride) vapor etch. Thus, a desired MEMS device is formed; the MEMSdevice has a particles blocking function, preventing particles fromfalling into the mechanical structure of the MEMS device.

Although the present invention has been described in detail withreference to certain preferred embodiments thereof, the description isfor illustrative purpose and not for limiting the scope of theinvention. For example, the materials, number of metal layers, etchdetails, and so on, can be modified without departing from the spirit ofthe present invention. One skilled in this art can readily think ofother modifications and variations in light of the teaching by thepresent invention. In view of the foregoing, it is intended that thepresent invention cover all such modifications and variations, whichshould interpreted to fall within the scope of the following claims andtheir equivalents.

1. A MEMS device with particles blocking function, comprising: asubstrate on which is formed a MEMS device region; and a particlesblocking layer deposited on the substrate.
 2. The MEMS device of claim1, wherein the particles blocking layer is made of a porous material. 3.The MEMS device of claim 1, wherein the particles blocking layer is madeof Black Diamond.
 4. The MEMS device of claim 1, further comprising apassivation layer formed between the substrate and the particlesblocking layer, the passivation layer being one selected from the groupconsisting of an oxide layer, an nitride layer, and a composite layerincluding an oxide layer and a nitride layer.
 5. The MEMS device ofclaim 1, further comprising a mask layer located between the substrateand the particles blocking layer or above the particles blocking layer,the mask layer being made of a material selected from poly-silicon,amorphous-silicon, and metal.
 6. A method for making a MEMS device withparticles blocking function, comprising: providing a substrate; forminga MEMS device region on the substrate; and depositing a particlesblocking layer for blocking particles.
 7. The method of claim 6, whereinthe particles blocking layer is made of a porous material.
 8. The methodof claim 6, wherein the particles blocking layer is made of BlackDiamond.
 9. The method of claim 6, further comprising: depositing andpatterning a mask layer.
 10. The method of claim 9, further comprising:performing an etch step according to the pattern of the mask layer. 11.The method of claim 9, wherein the mask layer is made of a materialselected from poly-silicon, amorphous-silicon, and metal.